Six Islamist terror suspects, including an alleged would-be suicide bomber, will be free to walk the streets by the end of the year after measures restricting their movements expire, the Government’s anti-terror watchdog warned yesterday.

One, a 24-year-old British citizen, is suspected of involvement in a 2006 plot to bring down a transatlantic flight in a suicide bomb attack. In a report, David Anderson, QC, said the six would be “free and unconstrained” because they could be monitored for a maximum of only two years under the Government’s Terrorism and Investigation Measures, unless new evidence was found against them.